The present invention relates to a set of golf clubs, and in particular, to a set of golf clubs having a maximum effective moment of inertia.
The playing of the game of golf and the equipment used therewith are controlled by the United States Golf Association rules of golf, which are designed to preserve the essence of the game by not allowing equipment producing improvements outside the skill level of the player. For this reason, and given the fact that the equipment works well, golf equipment has stayed generally constant over time, the exception being the progression from wooden golf clubs to more technically advanced metals, graphites, and other plastics, which are currently in use today.
Golf is played with a set of golf clubs, each individual club being designed to hit certain types of golf shots and/or to hit the golf ball certain distances depending upon the player's position and distance from the target, the hole. Within these parameters, there are a wide variety of numbers and types of golf clubs which comprise a set. Normally, a set of clubs totals fourteen, the maximum number allowed when playing a game in accordance with United States Golf Association rules. Such a set includes three to five woods, a putter and the remainder being irons. Individual golfers often vary the makeup of each set of golf clubs. For example, a set can be made of only one or two wood type clubs, the rest of the set being distributed among irons and a putter. The distribution of the various clubs generally provide a golfer with a series of different lengths, weights and lofts of club heads, which enable the golfer to hit shots of varying distance and trajectory, depending upon the particular golf shot required when playing a game of golf on a golf course. Traditionally, wooden type golf clubs are used to hit the ball greater distances, whereas the iron type golf clubs hit shorter and more controlled golf shots. Most golf clubs used today are matched in accordance with swing weight, and in an optimum set, shaft frequency. Swing weight process is a system of static measurements based on a linear function of the shaft, grip and head in relationship to each other, using a swinging weight matching scale as described in the U.S. Pat. No. to Adams (1,953,916). The clubs of such a conventional matched set balance at the same setting on the scale. The scale reading is then used to designate the swing weight characteristics of the set to provide a statically balanced golf club. This process of swing weight measurement gained wide acceptance because most of the shafts used were relatively of the same dead weight. However, with modern technology. There are great weight differences in shafts due to new materials available, and the idea of swing weight is less applicable because this traditional way of matching golf clubs creates a set which does not swing the same. Conventional golf clubs are statically matched rather than being dynamically matched, so that the clubs within the set are not matched when they are swung to hit a golf ball.
The concept of dynamically matching a set of golf clubs in accordance with the moment of inertia has been addressed in the prior art. For example, the U.S. Pat. No. to Marciniak (3,473,370) discloses a method of producing a dynamically matched set of golf clubs having the same moment of inertia by selecting a club of a desired swinging and playing action and determining its moment of inertia. This is accomplished using a torsional pendulum and measuring the moment of inertia with respect to the center of gravity. A set is made by selecting other clubs and applying heads of different weights until measurement with the torsional pendulum indicates that the same moment of inertia has been obtained. The data is plotted on a graph, which then can be read for the required head weights for the complete set.
The U.S. Pat. No. to Everett, III (3,698,239) relates to a dynamically matched set of golf clubs also having identical moments of inertia with respect to a common swinging axis. Using a selected club, the moment of inertia is determined by calculation from length and weight parameters. The head weights required for dynamically matching other sets in the club are matched to the favorite club.
The U.S. Pat. No. to Osborne et al. (3,703,824) relates to an apparatus for comparing moments of inertia of golf clubs about a given axis using a balance beam on a fulcrum, a means for supporting a club and a weight adapted to slide along the balance beam for counterbalancing the shaft and head, and a second weight on the beam between the fulcrum and the head whereby the two counterweights move over separate scales. The first scale is positioned on part of the beam and calibrated in units of moment of inertia, and the second scale positioned on another part of the beam, calibrated in length of the golf club. To make a set of clubs, each club is chosen such that its moment of inertia about a specific axis does not vary by more than a preset amount.
The U.S. Pat. No. to Suganuma (4,900,025) relates to a dynamically matched set of golf clubs using a uniform grip weight, shafts having different lengths and different shaft deflection characteristics. When a given torque is applied to each club about the same reference point, moments of force at the head and sides of the club are standardized with reference to a central portion between the hands of the player who holds a club during a swing about a rotating axis. When natural frequencies of the club head end are set and measured with reference to the central portion as a support end, the natural frequency of arbitrary clubs are fixed in accordance with a predetermined formula.
The U.S. Pat. No. to Turley (4,212,193) is directed to an apparatus and method for determining the moment of inertia of golf clubs using a low-cost electronic means to measure periods of oscillation and to compute and display the moment of inertia thereby. The patent teaches that clubs are matched by adding weight or adjusting length in order that the moment of inertia of each golf club be matched.